Field of the Disclosure
The present disclosure relates to a tool changer that changes a tool attached to a tool spindle of a machine tool with a next tool positioned at a predetermined position.
Background of the Disclosure
Tool changers typically change a tool attached to a tool spindle with a next tool by causing a plurality of tool holding units provided on a tool change arm to hold the tools, and the tool changer is classified into two different types, i.e. so-called swing type and insertion type, based on its behavior for causing the tool holding units to hold the tools.
The swing type tool changer typically includes a tool change arm having a tool holding unit at both ends thereof, which has an opening in an end-side side surface of the tool change arm, a support shaft provided in parallel to a tool spindle of a machine tool for supporting the tool change arm, and a rotation drive motor. Further, the swing type tool changer includes a rotating mechanism that rotates the tool change arm about an axis of the support shaft by using rotational power of the rotation drive motor, an advancing and retreating mechanism that includes an advancing and retreating drive motor and a ball screw, and advances and retreats the tool change arm along the support shaft with the ball screw driven by the advancing and retreating drive motor, and other components.
In this swing type tool changer, first, the tool change arm is rotated about the axis of the support shaft to cause one and the other of the tool holding units of the tool change arm to hold a tool attached to the spindle (first tool) and a next tool (second tool) positioned at a standby position, respectively. Subsequently, the tool change arm is advanced or retreated along the support shaft to pull the first tool out of the tool spindle and the tool change arm is rotated 180 degrees about the axis of the support shaft. Thereafter, the tool change arm is advanced or retreated along the support shaft to attach the second tool to the spindle. Thus, the first tool attached to the tool spindle is changed with the second tool.
Further, as for the above-mentioned insertion type tool changer, an automatic tool changer disclosed in Japanese Examined Patent Application Publication No. S47-33112 has been proposed. This insertion type tool changer includes a spider arm having four arms (first to fourth arms) provided thereon at 90 degree intervals, which arms each have a tool holding unit having an opening in the end surface of the arm, a drive mechanism that rotates the spider arm in a normal direction about a center axis parallel to a tool spindle of a machine tool, and advances and retreats the spider arm along the center axis, a tool transfer mechanism that transfers a tool to a standby position, and other components. When machining a workpiece, it is possible to cause the tool holding units of the first to fourth arms to hold, for example, a tool to be used first (first tool), a tool to be used next (second tool), a tool to be used after the next tool (third tool), and a tool to be used after the after-next tool (fourth tool) in sequence in the opposite direction to the rotating direction of the spider arm in advance.
When tools are changed by this tool changer, first, the first tool holding unit, which is empty because it has passed the tool to the tool spindle, is indexed to a tool change position by rotating the spider arm in the normal direction with the drive mechanism. Subsequently, the first tool attached to the tool spindle is moved to the tool change position so that it enters the first tool holding unit through the opening of the first tool holding unit, and the tool is held by the first tool holding unit. Thereafter, the spider arm is advanced or retreated to pull the tool out of the tool spindle, and then the spider arm is turned 90 degrees about the center axis to position the second tool held by the second tool holding unit in the tool change position and position the tool pulled out of the tool spindle in a standby position. Thereafter, the second tool is attached to the tool spindle by advancing or retreating the spider arm. Thus, the first tool attached to the tool spindle is changed with the second tool. Note that the first tool pulled out of the tool spindle is attached to an appropriate holding unit of the tool transfer mechanism and then stored into a tool magazine by the tool transfer mechanism.